Method and apparatus for increasing the speed of clothes dryers



United States Patent 3,319,347 METHD AND APPARATUS FOR INCREASING THE SPEED F CLOTHES DRYERS John D. Bentley, 69 Columbia St., Pasadena, Calif. 91105 Filed .lune 29, 1964, Ser. No. 378,621 4 Claims. (Cl. 34-32) The conventional method of operation of a clothes dryer at the present time is to heat air from the surrounding atmosphere and to pass that air through the clothes to be dried in a tumble enclosure and then to dispose of that air through an exhaust vent. There is a limitation to the speed that such a system can dry clothes. The humidity of the surrounding atmosphere, if it is high in water content, can be a detrimental factor in the clothes drying process. Air with a high water content cannot be expected to absorb a much greater amount of water in its passage through the wet clothes. Heating the air before passing it through the clothes increases its water capacity, but 'the total capacity is still low.

If the water content of the air to be used in the drying process could be substantially lowered prior to its passage through the clothes the overall speed of the drying Vprocess could be greately increased. Also, if some of the heat formerly disposed into the atmosphere could'be retained and used again, the eiiiciency of the system could be improved at the same time with a corresponding lower cost of operation than would otherwise be the case.

The object of this invention is to provide a system wherein the wet air having just previously passed through the clothes is mechanically dried by an apparatus that separa-tes the water from the air.

Another object of this invention is to provide supporting apparatus for the mechanical air dryer that features: High pressure air tiow from a tumble enclosure to the mechanical air drying apparatus. Air flow from the mechanical air drying apparatus through a suitable air heater and back to the tumble apparatus.

A further object of this invention is to show how the action of the mechanical air drying apparatus separates the water from the air in such a way that some of the heat in the air is preserved thereby improving the efficiency of the system.

These and further objects of this invention will become apparent as a careful study is made of the following description of the method and apparatus taken in conjunction with the accompanying drawing Where:

FIGURE l is a schematic drawing of the entire drying system;

FIGURE 2 is la side view of a Hilsch tube;

FIGURE 3 is a sectional view of the Hilsch tube taken on line 3 3 of FIGURE 2; and

FIGURE 4 is a section-al view of the Hilsch tube taken on line 4 4 of FIGURE 2.

The Wet clothes that are to be dried are placed in a conventional tumble enclosure 1. They are tumbled in such a manner that dry warm air from inlet 2 passes feely through all of the clothes in the Itumble enclosure 1. Evaporation of the water in the clothes takes place so that when the air is directed out of the tumble enclosure through outlet 3 it is saturated with moisture. The moist air then is directed to pump 4 where it is -pumped at high pressure into the Hilsch tube 5. The Hilsch tube 5 acts on the moist air and separates the water from the air. Most of the water and a small portion of Ithe air in the system passes out of the system and into any suitable drainage system connected in a conventional manner through pipe `6. Most of the air which has retained a good portion of the heat that was in it prior to its entry into the Hilsch tube 5 passes out of the Hilsch tube 5 ICC through pipe 7. At junction 8 any air that was lost to the system through the action of the Hilsch tube 5 is replace-d by the action of any suitable air bleed mechanism 9. The air is then passed to an optional blower 10v which returns the air to the inlet of the tumble enclosure through .a conventional air heaterl ,11j

The operation of the Hilsch tube 5 is as follows:

The pump 4 pumps the moist air at high pressure into the inlet 12 of .the Hilsch tube `5. The inlet [l2 narrows to a smaller diameter before entry 13 into the' vortex chamber 14 so that the moist air gains velocity. The air then travels around the perimeter of the spiral wallvlS of the vortex chamber 14. The action of the spiral ow of the moist air tends Ito send the hotter and heavier molecules to the periphery of the vortex chamber 14 and the'remaining colder and dried ymolecules stay in the center of the chamber. lNote the distance 16 between the edge of the spiral wall 15 and the outlet 13. This distance 16 helps with the separation of the hot and cold molecules. The cold and dry molecules in high concenltration at the center of the vortex chamber 14 pass through the hole 17 and down a short pipe 18 and then are connected with the pipe 7. The hot and wet molecules spin to the outside of the vortex chamber 14 and travel down a long pipe 19 where they pass through the output 20 which is regulated by the throttle 21 and which is connected to the output pipe 6.

Theory of operation of the Hilsch tube There are many conicting thories on the operation of the Hilsch tube. It is not the purpose of this invenltion to explain the myriad of complexities surrounding the operation of a phenomenon that is seemingly simple, but in fact has dozens of independent factors. Nobody can sayfor sure just what happens in the vortex chamber of the Hilsch tube, but what seems to happen will be suicient explanation for the layman.

Moist air enters the vortex chamber and spins varound in the chamber at great speed creating tremendous -centiflugal forces on the individual molecules in the moist air. The moist air enters the chamber at a direction not tangential to the spiral wall. It enters at an angle that leads it into violent collision with the spiral wall soon after entry into the vortex chamber. The molecules coming into the chamber are air with atomic weight of about 14.4 and water with atomic weight of about 18.0. The water molecules therefore have more momentum and thus more energy and activity than the air molecules. There is also a deviation in the activity of the air molecules admitted. There are cold molecules of low activi-ty, hot molecules of high activity, and molecules of average `temperature or activity.

When the molecules enter the vortex chamber they crash into the spiral wall. They are deflected toward the center of the vortex chamber. The colder air molecules because of their smaller amount of energy are deflected toward the center of the chamber a greater amount than the air molecules with greater energy and the Water molecules with greater mass and energy. The resulting centrifugal action of the vortex chamber allows the heavier and .more active molecules to go to the periphery of the chamber and the lighter and less active molecules to go to the center of the vortex cham-ber. The lighter and less active molecules tend to leave the vortex cham-ber through the route of least resistance which is the small hole at the side of the vortex chamber. The heavier and more active molecules spin to the outside and tend to exit the vortex chamber Ithrough their path of least resistance which is the long pipe with the throttle at the end.

Maximization of the drying power of the Hilsch tube is accomplished in two ways. First the size of the small hole in the side of the vortex chamber may -be varied larger or smaller. Second the opening of the throttle at the end of the long pipe can be opened or closed. Varying the size of the hole in the side of the vortex chamber fixes -the portion ot the energy spectrum that will go to the short pipe or cold outlet of the `Hilsch tube. It must be remembered that the colder molecules go to the center of the vortex chamber. The coldest molecules are the nearest to the center of the chamber and the energy of the molecules increases as they get further from the center. A very small hole will allow only the very coldest and driest molecules to be returned to the system. The result would be that too great an amount of =air at atmospheric humidity would have to be added to the system after the action of the Hilsch ltube. The action of the drying mechanism would then be carried on almost exclusively by the air in the surrounding atmosphere. The net result would be a complete negation of the purpose of the Hilsch tu'be and no more drying speed than conventional dryers.

If the hole in the side of the vortex chamber were too large almost all of the air in the system and the water too would pass through the hole and back into the system. The net result would be `a recycling of wet air vancl little or no drying action.

The throttle at the end of the long pipe can be opened and closed in order to restrict or encourage ow through the long pipe. The pressures in the pipe affect the action of the vortex chamber and the ow through the small hole in the side of the vortex chamber. The eiciency and performance of a speciiic Hilsch .tube can also be optimized by varying the size of the small `outlet hole until a desired degree of dehumidi-fcation is achieved.

By experimenting with different sized holes and different throttle settings the positions for the greatest drying power can be discovered for every design of the Hilsch tube.

I claim as my invention:

1. An improved dryer for drying damp articles, comprising:

heating means having an inlet to receive air and having yan outlet for delivering warmed air;

enclosure means defining a tumble enclosure for receiving and agitating the damp articles, and having an inlet coupled to the heating-means outlet Ito receive the warmed air, and an outlet for exhausting humid air;

a pump coupled to the enclosure-means outlet to receive and pressurize .the humid air, the pump having an outlet;

a Hilsch tube having an inlet coupled to the pump outlet to receive the pressurized humid air, and having a vortex chamber with -opposed first and second end walls, the first wall having an axial -ou-tlet, -and Ithe second wall having an outlet including throttling means for controlling flow, the Hilsch tube being operative to separate the incoming pressurized humid air into a stream of low-humidity air directed to the axial outlet and a stream of high-humidity air directed to the second-wall `outlet and throttling means; and

conduit means coupled to .the Hilsch-tube axial outlet and to the heating-means inlet for directing the stream of low-humidity air from the Hilsch tube to the heating means.

2. The dryer defined in claim 1 in which the Hilsch tube inlet has a downstream end which is spaced from the periphery of the vortex chamber.

3. The dryer defined in clai-rn 1 in which the conduit means includes means for admitting outside air to the conduit, and further includes a blower for repressurizing air delivered to the heating-means inlet.

4. A method of improving the efliciency of a dryer, comprising the steps of:

(a) pumping humid air from the dryer into a Hilsch tube whereby the humid air is separated into a stream of low-humidity air and a stream of high-humidity air;

(b) recirculating the stream of low-hu-midty air through a heater to the dryer.

References Cited by the Examiner UNITED STATES PATENTS 2,016,552 10/1935 McCreery 34--131 2,712,183 7/1955 Jorgenson 34-131 2,818,719 l/8 Cline 34-76 X FREDERICK L. MATTESON, JR.,

Primary Examiner.

JAMES W. WESTHAVER, Examiner.

C. R. REMKE, Assistant Examiner. 

1. AN IMPROVED DRYER FOR DRYING DAMP ARTICLES, COMPRISING: HEATING MEANS HAVING AN INLET TO RECEIVE AIR AND HAVING AN OUTLET FOR DELIVERING WARMED AIR; ENCLOSURE MEANS DEFINING A TUMBLE ENCLOSURE FOR RECEIVING AND AGITATING THE DAMP ARTICLES, AND HAVING AN INLET COUPLED TO THE HEATING-MEANS OUTLET TO RECEIVE THE WARMED AIR, AND AN OUTLET FOR EXHAUSTING HUMID AIR; A PUMP COUPLED TO THE ENCLOSURE-MEANS OUTLET TO RECEIVE AND PRESSURIZE THE HUMID AIR, THE PUMP HAVING AN OUTLET; A HILSCH TUBE HAVING AN INLET COUPLED TO THE PUMP OUTLET TO RECEIVE THE PRESSURIZED HUMID AIR, AND HAVING A VORTEX CHAMBER WITH OPPOSED FIRST AND SECOND END WALLS, THE FIRST WALL HAVING AN AXIAL OUTLET, AND THE SECOND WALL HAVING AN OUTLET INCLUDING THROTTLING MEANS FOR CONTROLLING FLOW, THE HILSCH TUBE BEING OPERATIVE TO SEPARATE THE INCOMING PRESSURIZED HUMID AIR INTO A STREAM OF LOW-HUMIDITY AIR DIRECTED TO THE AXIAL OUTLET AND A STREAM OF HIGH-HUMIDITY AIR DIRECTED TO THE SECOND-WALL OUTLET AND THROTTLING MEANS; AND CONDUIT MEANS COUPLED TO THE HILSCH-TUBE AXIAL OUTLET AND TO THE HEATING-MEANS INLET FOR DIRECTING THE STREAM OF LOW-HUMIDITY AIR FROM THE HILSCH TUBE TO THE HEATING MEANS. 